Just read the Wiz changes presentation and the story frim Blizzard behind Hydras.
Have to say I liked it very much. Good to see there's a chance to see wizards with Hydras OTHER than systematically Venom one.

And while reading these lines, when arrived the moment where Blues were saying "we're not 100% sure yet what we want to do to flavour properly the Mammoth Hydra" some wild idea just popped in my head. The more I think about it, the more I think it is feasible, shouldn't be too hard to balance, and more or less suits quite well the concept of "Mammoth" Hydra.

I guess we will all agree that a Mammoth is a big massive beast that gets rid of annoyances by just trampling them with a good charge.

So what about : Whenever you "re-summon" your Mammoth Hydra, it doesn't just "de-pop" from its location and "appear magically" at the new location, but in fact it will kind of "charge" from its location to the new one, trampling and damageing all in its path ? (potentially knocking back or stunning eventually). This would totally fit as well the "good in hallways" cause it would guarantee you trample EVERY FREAKING THING in that corridor every time your Hydra goes for a charge. Might have to tune a bit the mana costs to ensure one can't just "trample his way constantly, everywhere, everytime, continuously", but it appears as potentially fun and "fitting with the concept" to me.